Nonwoven fabric having improved air permeability and manufacturing method thereof

ABSTRACT

A nonwoven fabric having improved air permeability and manufacturing method thereof are presented. The nonwoven fabric has improved air permeability and is formed with long fiber nonwoven fabric of single or multi layer, wherein the long fiber nonwoven fabric is produced by spinning polytrimethylene terephthalate having viscosity of 0.8 to 1.2 and polyethylene terephthalate having viscosity of 0.6 to 0.8 to sheath/core shape with using each spinneret pack which can spin filaments having different denier from each other and arranged in parallel with each other, and then heat pressing with free-embossing or embossing pattern to bind the filaments. 
     The nonwoven fabric has excellent air permeability, softness and resistance, which are required for nonwoven fabric sheets used for various purposes as well as their economical production.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a nonwoven fabric having improved air permeability and manufacturing method thereof, and more particularly to a nonwoven fabric having improved air permeability, in which the nonwoven fabric has excellent air permeability while maintaining a former physical property of the prior nonwoven fabric made of poly trimethyleneterephthalate which has proper durability and softness to be required as an agricultural sheet that can control growth of weeds by covering a soil being planting with the corps, and can be useful as agricultural sheet being capable of produced economically, but has a drawback that its air permeability is unsatisfied, and the method for manufacturing the nonwoven fabric having improved air permeability.

2. Description of the Prior Art

It is common method to defoliate the weeds by spraying herbicide or to root up it with manual labor as weed-proofing or weeding. However, the method of using herbicide is not preferable since it contaminates the soil or kills a microorganism at the soil which will be beneficial on the growth of plants, so that it can be result in devastation of the soil. Therefore, to solve such conventional problem, the nonwoven fabric has been used to inhibit growth of the weed by inhibiting photosynthesis. Particularly, with covering the soil of agricultural land planted with various crops with nonwoven fabric, while suppressing the growth of weeds, the air is permeated and the soil is warmed so that the growth of crops can be facilitated. Therefore, the sheet which is configured to fit the above object is widely used in agriculture. As such nonwoven fabric for agriculture, a polyolefin-based, especially a polypropylene-based spunbond nonwoven fabric considering the sides of economy as a raw material has been proposed and has been used. More specifically, the said agricultural nonwoven fabric, for example, nonwoven fabric which is constructed by using a synthetic fiber filament yarn made of a polypropylene resin is provided which one side of the nonwoven fabric is partially thermocompression bonding embossing process or a non-woven fabric is produced with free embossing.

For example, Korean patent early publication 2002-36636 describes, with the title of “nonwoven fabric for agriculture”, nonwoven fabric which synthetic fiber filament yarn of 2-3 denier is arranged with the density of 55˜65 g/m² smoothly, and then heat-pressed with a roller press to be embossed on one or both sides. These nonwoven fabrics for agriculture have a relatively good mechanical properties and its handling is easy. Also, these nonwoven fabrics have effects that the contact area with air becomes large by concave-convex parts of embossing so that the permeation of air is seamlessly. However, these nonwoven fabric thicken not to achieve an optimal air flow, and to increase the shielding degree of light, so that the corps take the rootlet into these nonwoven fabric due to misconception as soil and then the corps is withered when dry whether. Therefore, it is necessary a solution for this problem and various methods have been proposed to solve it. Such as the pre-mentioned description, the approach for improving the nonwoven fabric for agriculture relates, for example physical properties of nonwoven fabric, since the conventionally proposed nonwoven fabric for agriculture has drawback that its thick is excess and an air flow is not smooth, and a content of moisture is also excess so that there is a problem that it is difficult to achieve the original object as an inhibition of growth of weed.

But, the conventional nonwoven fabric for agriculture has a drawback that its strength and resistance is insufficient to use as an agricultural usage, although the conventional nonwoven fabric for agriculture has economical advantage since the polypropylene made of it can be produced at low cost.

On the other hand, as those having good resistance, polytrimethylene terephthalate (PTT) had been provided with the nonwoven fabric and synthetic fibers of various kinds. For example, Korean Patent Application No. 2002-0049047 describes a preparing method of polytrimethylene terephthalate staple fiber which comprises a step of (a) supplying polytrimethylene terephthalate, (b) spinning melted polytrimethylene terephthalate at a temperature of 245-285° C. to a filament, (c) quick quenching the filament, (d) extending the quenched filament, (e) winding the extended filament with 8 to 30 winding orders/inches (3 to 12 winding orders/cm) by using a mechanical winder, (f) relaxing the winded filament at a temperature of 50-120° C., and (g) cutting the relaxed filament with a staple fiber of a length of 0.2 to 6 inches (about 0.5 to 15 cm). Also, Korean Patent Application No. 2003-0070138 describes a polyester-based latent-crimping conjugated fiber and method for preparing the same. Japanese patent publication No. 2001-146671 describes a long fiber nonwoven fabric, Japanese patent publication No. 2003-306863 describes a polyester filament nonwoven fabric and a separation membrane using the same, and Japanese patent publication No. 2002-180366 describes a filament nonwoven fabric having excellent formability.

But, the prior art such as the said one never describes and suggests for a nonwoven fabric and producing method thereof which has a physical property suitable for the nonwoven fabric for agriculture while it has air permeability above a desired level as an economical nonwoven fabric by using PTT. Therefore, it is acutely needed to provide for a nonwoven fabric having air permeability above a desired level, while it keeps a physical property of PPT nonwoven fabric according to the prior art.

SUMMARY OF THE INVENTION

Accordingly, the present invention has been made in view of the problems occurring in the prior art, and it is the main purpose of the present invention to provide a nonwoven fabric having excellent air permeability as well as soft property and proper resistance of the prior PPT nonwoven fabric and being capable of produced economically.

Another object of the present invention is to provide a production method which can solve the above-described problems occurring in the prior art, and thus can more easily produce nonwoven fabric having the said excellent property.

Still another object of the present invention is to achieve other objects which can be easily conceived by a person skilled in the art from the above-described clear objects and the description of the specification of the present invention.

As the result of investigation for method improvable air permeability with keeping soft property and resistance of the prior PPT nonwoven fabric excellently, the said object of the present invention can be achieved by producing PPT nonwoven fabric with using a general spinneret mixed with a spinneret for coarse denier and then by optimizing a procedure condition.

To achieve the above objects, in one aspect, the present invention provides nonwoven fabric having improved air permeability which is formed with long fiber nonwoven fabric of single or multi layer, wherein the long fiber nonwoven fabric is produced by spinning polytrimethylene terephthalate having viscosity of 0.8 to 1.2 and polyethylene terephthalate having viscosity of 0.6 to 0.8 to sheath/core shape with using each spinneret pack which can spin filaments having different denier each other and is arranged in parallel with each other, and then heat pressing with free-embossing or embossing pattern to bind the filaments.

In a preferred embodiment of the present invention, the component ratio of polytrimethylene terephthalate and polyethylene terephthalate constituting the said nonwoven fabric is polytrimethylene terephthalate of 10 to 50% by weight with respect to total weight.

In a preferred embodiment of the present invention, a basic weight of the said nonwoven fabric is 40 to 100 g/m².

In a preferred embodiment of the present invention, the denier of filament consisting of the said nonwoven fabric is at least 2 to maximum 12 deniers.

In a preferred embodiment of the present invention, the air permeability of the said nonwoven fabric is above 200 ccs.

In another aspect, the present invention provides a method for producing nonwoven fabric having improved air permeability, the method comprising the steps of:

drying polyester having intrinsic viscosity of 0.6 to 0.8 and melting point of 260° C. and polytrimethylene terephthalate having viscosity of intrinsic viscosity of 0.8 to 1.2 and melting point of 225° C. in each dryer to moisture contents of below 100 ppm, and crystallizing and then providing it with an extruder;

spinning to sheath/core shape with using each spinneret pack which can spin filaments having different denier each other and is arranged in parallel with each other, wherein a filament is formed such that the spun polytrimethylene terephthalate is to 10-50% by weight with respect to total weight;

cooling the filament with cooled air, and consolidating it to prevent welding among the filament;

elongating and dispersing the filament by crashing it to an impinging plate with certain velocity and angle to form a web;

stacking the prepared filament uniformly on the moving conveyer belt successively to form a web by using a suction device at below; and

thermally bonding the said stacked filament web by using the calendar which has the upper roll set at temperature of 180-210° C. and the lower roll set at temperature of 188-208° C., and nip pressure of 30-100 kg/cm, and whose bonding rate is 10-30%.

Being constituting as the above, the nonwoven fabric having improved air permeability and the method for producing thereof according to the present invention is constituted mainly polytrimethylene terephthalate and additionally polyethylene terephthalate, and produced by spun with a filament of different denier after mixing the said component, so that the said problem at prior art can be solved to provide a nonwoven fabric having excellent air permeability as well as soft property and proper resistance which is required for the nonwoven fabric sheet of various usage and to make it possible to produce it economically.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, the present invention will be described in further detail with reference to preferred embodiments. It is to be understood, however, that the scope of the present invention is not limited to these embodiments.

The PTT nonwoven fabric having improved air permeability according to the present invention may be constructed with single layer or multi layer structure of spunbonded nonwoven fabric sheet and/or meltblown nonwoven fabric sheet and is constructed by heat-pressing nonfabric tissue under certain pressure and certain temperature.

The said PTT nonwoven fabric having improved air permeability of the present invention is preferably formed with long fiber nonwoven fabric of single or multi layer, wherein the long fiber nonwoven fabric is produced by spinning polytrimethylene terephthalate having viscosity of 0.8 to 1.2 and polyethylene terephthalate having viscosity of 0.6 to 0.8 to sheath/core shape with using each spinneret pack which can spin filaments having different denier each other and is arranged in parallel with each other, and then heat pressing with free-embossing or embossing pattern to bind the filaments.

According to a preferred embodiment of the present invention, the component ratio of polytrimethylene terephthalate and polyethylene terephthalate constituting the nonwoven fabric according to the present invention is polytrimethylene terephthalate of 10 to 50% by weight with respect to total weight. In case of being weight rate of the said polytrimethylene terephthalate below 10% by weight, a soft property of the nonwoven fabric is not sufficient so that workability becomes wrong at using the product. In contrary, in case of being weight rate of the said polytrimethylene terephthalate exceed 50% by weight, it is not preferable since the strength is declined and the cost for production is increased.

In a preferred embodiment of the present invention, a basic weight of the said nonwoven fabric is preferably 40 to 100 g/m².

In a preferred embodiment of the present invention, the denier of filament consisting of the said nonwoven fabric is preferably at least 2 to maximum 12 deniers, and the air permeability of the said nonwoven fabric is preferably above 200 ccs.

According to a different preferred embodiment of the present invention, the fabric constituting the said nonwoven fabric may preferably comprise the UV stabilizer of 6.0-9.0 parts by weight which contains Hindered amine light stabilizer of 0.1-1.5 parts by weight based on the fabric 100 parts by weight, to increase a weatherproof. In case of being the added amount of UV stabilizer below 0.1 parts by weight with respect to total PPT or PPT and PET resin, an effect of weatherproof is insufficient, and in case of being the added amount of UV stabilizer exceed 1.5 parts by weight, it is not preferable since the workability is poor such that pressure increases and yarn cutting occurs, and the cost for production is increased.

According to yet another preferred embodiment of the present invention, it is preferable to dry polyester having intrinsic viscosity of 0.6 to 0.8 and melting point of 260° C. and polytrimethylene terephthalate having viscosity of intrinsic viscosity of 0.8 to 1.2 and melting point of 225° C. in each dryer to moisture contents of below 100 ppm, and to crystallize and then provide it with an extruder, and to spine to sheath/core shape with using each spinneret pack which can spin filaments having different denier, each other and is arranged in parallel with each other. If the said spinneret pack which can spin filaments having different denier each other is arranged in a random pattern, it is difficult to make a producible product due to excessive variation of air permeability between parts even though the total air permeability of nonwoven fabric may become good. If the said spinneret pack is arranged in a alternation pattern, there is a drawback that it is impossible to form a web because a web shape formed by filaments of thin denier is different from a web shape formed by filaments of thick denier.

According to a preferred embodiment of the present invention, a method for producing nonwoven fabric having improved air permeability according to the present invention comprises the steps of drying polyester having intrinsic viscosity of 0.6 to 0.8 and melting point of 260° C. and polytrimethylene terephthalate having viscosity of intrinsic viscosity of 0.8 to 1.2 and melting point of 225° C. in each dryer to moisture contents of below 100 ppm, and crystallizing and then providing it with an extruder; spinning to sheath/core shape with using each spinneret pack which can spin filaments having different denier each other and is arranged in parallel with each other, wherein a filament is formed such that the spun polytrimethylene terephthalate is to 10-50% by weight with respect to total weight; cooling the filament with cooled air, and consolidating it to prevent welding among the filament; elongating and dispersing the filament by crashing it to an impinging plate with certain velocity and angle to form a web; stacking the prepared filament uniformly on the moving conveyer belt successively to form a web by using a suction device at below; and thermally bonding the said stacked filament web by using the calendar which has the upper roll set at temperature of 180-210° C. and the lower roll set at temperature of 188-208° C., and nip pressure of 30-100 kg/cm, and whose bonding rate is 10-30%.

Hereinafter, the present invention will be described in detail with reference to the following examples, but the scope of the present invention is not limited to those examples.

EXAMPLE 1

Polyester having intrinsic viscosity of 0.65 and melting point of 260° C. and polytrimethylene terephthalate having viscosity of intrinsic viscosity of 1.02 and melting point of 225° C. were dried in each dryer to moisture contents of below 100 ppm respectively, and crystallized and then provided with each extruder which temperature of each zone was set at 280° C. and 260° C. respectively. And it were supplied to each spinneret pack of sheath/core shape through each supplying pump, wherein the said packs were consisted of a pack having 52 spinneret holes of diameter of 0.28-0.60 mm and a pack having 240 spinneret holes and were arranged in parallel with each other. Wherein a filament was formed such that the spun polytrimethylene terephthalate was to 20% by weight with respect to total weight, and two kinds of polyester was spun with 285 g per minute to form a filament. The filament was cooled with cold air from a quenching chamber, and consolidated it to prevent welding among the filament. And then the cooled filament was elongated through an ejector of air pressure of 3.5 kg/cm² to give a property as a filament. To form a web, the filament was dispersed by crashing it to an impinging plate with certain velocity and angle and stacked the said filament uniformly on the moving conveyer belt successively by using a suction device disposed at below of conveyer belt. Here, the velocity of conveyer belt was controlled to 22m per minute. To thermally bond the said web, the calendar was used which has the upper roll set at temperature of 200° C. and the lower roll set at temperature of 198° C., and nip pressure of 60 kg/cm, and whose bonding rate was 20%. The nonwoven fabric manufactured in this manner was measured for its properties as following experimental example, and the measurement results were shown in Table 1.

EXAMPLE 2

The nonwoven fabrics were manufactured using the same procedure as Example 1 above in the same condition as Example 1 except that polytrimethylene terephthalate was input to 50% by weight with respect to total weight. The nonwoven fabric manufactured in this manner was measured for its properties, and the measurement results were shown in Table 1.

COMPARATIVE EXAMPLE 1

The nonwoven fabrics were manufactured using the same procedure as Example 1 above in the same condition as Example 1 except that polytrimethylene terephthalate was input to 30% by weight with respect to total weight. The nonwoven fabric manufactured in this manner was measured for its properties, and the measurement results were shown in Table 1.

COMPARATIVE EXAMPLE 2

The nonwoven fabrics were manufactured using the same procedure as Example 1 above in the same condition as Example 1 except that a pack having 52 spinneret holes and a pack having 240 spinneret holes were arranged in alternation pattern. The nonwoven fabric manufactured in this manner was measured for its properties, and the measurement results were shown in Table 1.

EXPERIMENTAL EXAMPLE

The nonwoven fabrics manufactured in the manner of Examples and Comparative examples were measured for its properties as followings:

(1) weight per unit area (weight: g/m²): it was measured according to the method of ASTM D 3776-1985.

(2) tensile strength: the maximum load was obtained according to the method of ASTM D 1682-64 using the tensile strength and extensometer device (Instron), under condition of sample piece width of 5 cm, its interval of 7.5 cm and tensile velocity of 300 mm/min.

(3) tensile extension: the extension degree was obtained when being maximum extension according to the above method (2).

(4) air permeability: the amount of air which flows after passing through a certain area of the nonwoven fabrics vertically was measured by using an orifice (circular sample piece grasping device) which can test an area of 38 cm² by the method of KS K 0570.

(5) thickness: it was measured by using the dial gauge.

TABLE 1 Compar- Compar- ative ative Item Unit Exp. 1 Exp. 2 Exp. 1 Exp. 2 Total weight gsm 80 80 80 80 PTT contents % 80 50 30 80 PET contents % 20 50 70 20 Arrangement parallel parallel parallel alter- shape of packs nation Temperature of ° C. 200 200 200 200 upper calendar Temperature of ° C. 198 198 198 198 lower calendar Strength (MD) kgf/5 cm 28.3 22.8 40.9 — Strength (CD) kgf/5 cm 14.5 12.1 25.7 — Extension (MD) % 48.2 57.6 12.4 — Extension (CD) % 45.6 55.7 20.3 — Thickness μm 0.31 0.34 0.35 — Air ccs 253 211 142 — permeability Spun property good good good spun and web impossible formability

Although the preferred embodiments of the present invention have been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanied claims. 

What is claimed is:
 1. The nonwoven fabric having improved air permeability which is formed with long fiber nonwoven fabric of single or multi layer, wherein the long fiber nonwoven fabric is produced by spinning polytrimethylene terephthalate having viscosity of 0.8 to 1.2 and polyethylene terephthalate having viscosity of 0.6 to 0.8 to sheath/core shape with using each spinneret pack which can spin filaments having different denier each other and is arranged in parallel with each other, and then heat pressing with free-embossing or embossing pattern to bind the filaments.
 2. The nonwoven fabric of claim 1, wherein the component ratio of polytrimethylene terephthalate and polyethylene terephthalate constituting the said nonwoven fabric is polytrimethylene terephthalate of 10 to 50% by weight with respect to total weight.
 3. The nonwoven fabric of claim 1, wherein a basic weight of the said nonwoven fabric is 40 to 100 g/m².
 4. The nonwoven fabric of claim 1, wherein the denier of filament consisting of the said nonwoven fabric is at least 2 to maximum 12 deniers.
 5. The nonwoven fabric of claim 1, wherein the air permeability of the said nonwoven fabric is above 200 ccs.
 6. The method for producing nonwoven fabric having improved air permeability, the method comprising the steps of: drying polyester having intrinsic viscosity of 0.6 to 0.8 and melting point of 260° C. and polytrimethylene terephthalate having viscosity of intrinsic viscosity of 0.8 to 1.2 and melting point of 225° C. in each dryer to moisture contents of below 100 ppm, and crystallizing and then providing it with an extruder; spinning to sheath/core shape with using each spinneret pack which can spin filaments having different denier each other and is arranged in parallel with each other, wherein a filament is formed such that the spun polytrimethylene terephthalate is to 10-50% by weight with respect to total weight; cooling the filament with cooled air, and consolidating it to prevent welding among the filament; elongating and dispersing the filament by crashing it to an impinging plate with certain velocity and angle to form a web; stacking the prepared filament uniformly on the moving conveyer belt successively to form a web by using a suction device at below; and thermally bonding the said stacked filament web by using the calendar which has the upper roll set at temperature of 180-210° C. and the lower roll set at temperature of 188-208° C., and nip pressure of 30-100 kg/cm, and whose bonding rate is 10-30%. 